Fontlab 5 exported font (OTF) kerning problem with specific letters

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Hossein Shahni's picture
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Joined: 1 Jun 2017 - 8:58am
Fontlab 5 exported font (OTF) kerning problem with specific letters
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Hey there everybody,
I've designed a Persian font (Arabic letters) in Fontlab 5 and exported it, but after I tested it in Adobe Illustrator to check if there's anything wrong with it I encountered a strange problem:
Some specific letters don't follow the kerning values I've designated to them when used before or after one another. For example, the letter "ا" (alef) doesn't follow the kerning values when used after "ر" (Re), "ز" (Ze), "ژ" (Je). There's also a problem with Re, Ze and Je when used after one another.
I've double checked the kernings and found no problem with them whatsoever. The only thing that I could think of as a potential cause was that I used an existing font as a reference to put the letters in the right place, I thought the original font might have additional properties which are causing the problem.
Any help would be appreciated.
Thanks